Spark-plug



J. SHARP.

SPARK PLUG. APPLICATION FILED APR. 5, l9l9- Patented Feb. 17,1920.

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JOHN SHARP, 0F CLEVELAND. OHIO.

SPARK-PLUG.

Specification. of Letters Patent.

Patented Feb. 17. 1920..

Application filed April 1919. Serial No. 287,900.

To all whom it may concern Be it known that 1, JOHN SHARP, a citizen of the United States, and resident of Cleveland, in the county of Cuyahoga and State of Ohio. have invented certain new and use ful Imprm'ements in Spark-Plugs, of which I hereby declare the following to be a full, clear. and exact description. such as will enable others skilled in the art to which it appertains to make and use the same.

The general object of this invention is to provide an improved construction for the firing terminals of a super-electric and mechanical high tension spark plug. which permits of the use of the plug in combustion chambers of all sizes and depths. and which permits of the use of one body common to any number of changeable terminals, to suit them to the varying depths of the different combustion chambers found in explosion engines.

A further object is to provide an independent body terminal. which will not be, affected by the expansion and contraction of the body of the plug. but will remain rigid and the sparking tips on the terminal will not sag or change their positions under any conditions in the combustion chamber when they have once been fixed or adjusted for use.

Further objects are to provide a unitary sparking member detachably secured to the body of the plug and formed in cylindrical shape and provided with integral sparking blades or tips which are spaced about the. central electrode and can be bent radially toward. or away from the same to regulate thewidth of the spark gap. The device is economically made and marketed since cue body and one insulation can be used with all lengths of terminals. and the substitution of one set of terminals for another can be quickly made. Also if either terminal should be destroyed it. can easily and quickly be replaced without renewing the entire spark plug.

The firing tips are also tapered so that the heat of the explosion will be sooner dissipated than when wire terminals are employed. The tapering bases of the tips also tend to make them rigid and remain where they are placed. They also provide an easy path for the electric current. The device is also simple in construction and comprises a cylindrical shell with integral attaching means and integral tapered and flattened sparking blades or tips. and wh ch can be made of rolled sheet metal or drawn or pressed from. or stamped from any metal suitable for the construction of firing terininals.

The invention is hereinafter further described shown in the accompanying drawings and specifically pointed 'out in the claims. In the accompanying drawings Figure 1 is a front elevation of the improved spark plug; Fig. 2 is a longitudinal central section therethrough; Fig. 3 is a ottom view thereof; Fig. lis a side elevation of the cylindrical terminal; Fig. 5 is a side elevation of a modified form construction of rolled sheet metal; Fig. G is a modified form of cimstruction of a terminal showing only one tip.

in these drawings. A is the metal body of the spark plu B is the porcelain core of insulation; C is the clamping sleeve; D and E are the compressible washers. which prevent the core from becoming cracked when the surrounding metal expands and also prevent leakage of gas through the interior of the plug: 1 is the central electrode, which passes axially through the core, and is provided with a shoulder G at one end and is screw threaded at the other end for attachment of the clamping nuts H and I. J is a cylindrical sleeve constructed of good conducting metal. which forms the body of the terminal. This sleeve tits tightly the sides of the central opening K in the inner end of the body. and makes electrical and mechanical contact or ground therewith. and is provided with a lateral iiange L at its upper end which is inclosed between the compressible washers E and M upon the shoulder N in the central opening in the plug. also making good electric connection therewith. The action of screwing down the clamping sleeve rigidly secures the shell in place. The central insulation extends downwardly at 0 some distance be yond the shoulder N to prevent inductive discharges from the central electrode to the inner sides of the shell .l. The outer cx tremity of the shell extends beyond the body of the plug and is provided with one or more sparking tips which are flattened at l to give a broad surface over which the Sparking can take place and which will be adapted to receive an intensive current. These tips are gradually widened from the comparatively broad extremities P. to where they join the body of the shell "to facilitate the flow of the current and to conduct the heat caused by the explosion rapidly away .radially inward toward the central electrode leaving a spark gap at Q of any desired width. It will be seen that when the shell is in position and rigidly fastened and the integral tips are bent into position. they will stay precisely where positioned and can be relied upon to always function properly since no amount of (ll i()ltl()l1 or expansion of the body of the plug can affect the individual rate of expansion of the shell and tips P.

Any number of tips from one upward can be used according to the intensity of the current employed. In Fig. r a stamped or drawn metal -shell is shown and in Fig. 5 a shell is shown formed of rolled metal, the ga at R being tightly closed to prevent lea age of current, and in Fig. (i a single tip P is shown with a detachable body terminal of this character. A large number of modifications can be made in the length of the shell to adapt it to combustion chambers of different sizes and depths from the outer surface of the cylinder or to penetrate the water casing, to enable the plug to extend to the required distance into the cylinder, and large number of sets of terminals of different lengths can be used selectively or iiiterchangeably with one spark plug and they can be changed at will to adapt them to required conditions, which could not be done if both the terminals were both stationary in the plug and not detachable therefrom. It is important that the tips P should be in-' tegral with the body of the shell since where the sparking tips can be moved or rotated in the shell, no reliance could be placed upon their action, for this reason that when the sparking tips are made of separate wire or other parts and are driven or forced or riveted in holes made in the plug body portion. they will eventually become loose in the holes and will move, or rotate, therein,causing the spark gap to be thrown out of adjustment. This will. in turn. cause the spark plug to miss fire and the motor to fail. The loosening of separate spark tips iscaused by the uneven expansion and contraction of different meta-ls used in the construction of the plug body and firing tips.

This cannot happen where the firing tips are unitary or integral with the shell and if the shell is flanged, and the flange is rigidly clamped in the plug, it would be impossible for the tips to become loose, because when the clamping nut is screwed. down tight to prevent the plug from leaking gas, the shell is securely held by the flange, and will expand and contract independently of the body of the plug.

Having described the invention. what I claim as new and desire to secure by Letters said tips turned upwardly and radially 110-" ward said central electrode. and means for securing said cylindrical terminal in place.

2. In a'spark plug. in combination. a body portion, a central insulation. and an electrode passing axially therethrough to a point beyond the inner end of said body portion. a horizontal shoulder in said body portion. and corresponding projection upon said insulation. a clamping sleeve for said insulation. the inner end of said body provided with a longitudinal recess. and a cylin' drical terminal inserted and fitting the body of said spark plug tightly in said recess. said terminal provided with a horizontal flange secured between said insulation and said shoulder and compressible washers between said flange and said shoulder and between said flange and insulation. the extremity of said cylindri *al terminal projecting beyond said body and provided with bladed sparking tips turned radially and upward toward said central electrode.

3. In a spark plug, a body. a central electrode, said body provided with a longitudinal opening at its lower end. an independent body terminal tightly secured in said opening and provided with a horizontal flange. said body provided with a corresponding horizontal shoulder. an adjustableclamping means for said flange. said clamping means extending within said body and integral sparking tips for said terminal, said tips directed radially inward and upwardly toward said electrode. the lower extremity of said independent body terminal provided with spaced longitudinal openings intermediate of said tips and extending up within the body of said spark plug providing space within said body for the free action of gases.

In testimony whereof I hereunto set my hand this 1st day of April. 1919.

JOHN SHARP.

In the presence of- Val. M. Moxnon, CHAS. F. Sum. 

